Add icon URLs

[edmundedgar]

Now that we have EIP-3085 it becomes useful for dapps to have a maintained list of parameters they can use to create "add network" requests. The chains.json here file works great for this purpose, except that it's missing a couple of fields:

• The block explorer, mentioned in Add BlockExplorer information #59
• The icon, which we see used here for example: https://forum.1hive.org/t/its-finally-here-the-custom-network-api/2659

We don't necessarily need them for all networks, just the main ones would be fine.

[ligi]

Yea - actually Icons are easier than the block explorer so I will start with this one.
I suggest to make it an array to cater for different sizes / formats and enforce the URL to be a web3 URL (ipfs:// to start with) so we can pin it in the process.
Does this work for everyone:

{
    ...
	"icon": [{
			"url": "ipfs://myIPFSurl",
			"width": 128,
			"height": 128,
			"format": "png"
		},
		{
			"url": "ipfs://myIPFSurlForSVG",
			"format": "svg"
		}
	]
}

where:

• URL must be a valid resolveable web3 URL that will be pinned in the process
• width, height are a number and optional (for vector assets)
• format is either jpg,png or svg

If we can get rough consensus around this I would add support for it to the CI and hope for some help with backfilling important chains.

[edmundedgar]

That looks good to me - I'm not sure whether metamask will handle raw ipfs urls correctly or not but if not I guess it's not a big deal for the code that consumes that to switch the ipfs:// URL to use a gateway.

[ligi]

yea - we could also offer a transformed json that changes the URLs to use a prefix

[ligi]

Just had one thought when starting to add support: maybe it makes sense to have the icon definitions in different files and just have references to it in the chain definitions.
Background: some chains will share the icon definitions (e.g. between main and testnets) so this would make things WET and IMHO we should keep things DRY.

[edmundedgar]

Sounds good to me, I guess that'll mean we'll definitely want to be able to generate a transformed json but that's probably a good idea anyhow